Device to test compression ratio.

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In Hemmings newsletter:

Katech develops new device to test compression ratio

Katech’s Whistler can read an engine’s compression ratio within one-tenth of a point.
photo courtesy Katech
Determining the compression ratio of an engine when the cylinder heads are off is fairly simple; with full access to the combustion chamber, you can gather the critical volumes and enter them into the proper formulas to come up with a figure. But with the engine buttoned up, it’s anyone’s guess how much squeeze is happening, unless the volume data was saved during assembly, and when working on stuff other people have put together, that sort of information is often unobtainable.

To overcome the frustration of having to take educated guesses at an engine’s compression ratio when tuning unfamiliar vehicles, Katech created the Whistler, an electronic device that can “read” combustion chamber volume via the spark-plug hole and determine the ratio within one-tenth of a point.

All that’s required to use the device is a 120-volt power feed and a low-volume compressed air source. The unit connects to the engine with a supplied spark-plug adapter fitting, and once the cylinder being sampled is turned to top-dead center, all the user has to do is enter the number of cylinders (4, 6 or 8 can be used), the cubic-inch displacement and the engine temperature, and the Whistler will calculate the compression ratio.

Katech says the unit is being used by some race sanctioning bodies to verify compression while avoiding teardowns, and it’s also very useful for performance tuning shops that deal with engines that were built elsewhere. The Whistler includes the necessary spark-plug adapters and a special bottle to check the calibration of the machine. Complete instructions are also included. To find out more, go to www.katechengines.com.
- By Terry McGean